Overhead rail supporting structure for photographic apparatus

ABSTRACT

In photographic apparatus, spatial adjustments of its optical head to a subject holder obtain along overhead rails which are supported on a long spanning member embodying interfitted channel members of folded heavy gauge sheet metal. Said spanning member rests at its opposed ends on two piers each comprising four spaced posts joined by cross beams adjacent their top and base. The composite structure affords a rigid and stable support for the head such that its film platen and lenses remain coaxially aligned with the subject holder through said spatial adjustments.

United States Patent [1 1 Wally, Jr. et al.

[54] OVERHEAD RAIL SUPPORTING STRUCTURE FOR PHOTOGRAPHIC APPARATUS [75]Inventors: Joseph H. Wally, Jr.; Samuel E. Wilson, both of Shawnee,Mission,

Kans.

[73] Assignee: Western Blue Print Co., Kansas City, Mo.

[22] Filed: May 28, 1971 [21] App1.No.: 147,762

[52] US. Cl ..355/5S, 355/56 [51] Int. Cl. ..G03b 27/52 [58] Field ofSearch ..355/l8, 55, 56, 58

[56] References Cited UNITED STATES PATENTS 2,585,927 2/1952 Gelb..355/55 X 2,229,761 1/1941 Mueller ..355/55 2,306,885 12/1942 Klemm etal. ..355/55 2,519,609 8/1950 Sussin ..355l55 [451 Apr. 3, 19732,989,893 6/1961 Wanielista et al ..355/55 2,402,107 6/1946 Wekeman..355/18 3,383,982 5/1968 Moss ....355/18 X 3,424,530 1/1969 Leonhart..355/l8 X Primary Examiner-Samuel S Matthews Assistant Examiner-RichardA. Wintercorn Attorney-Johnson, Dienner, Emrich, Verbeck & Wagner 57ABSTRACT In photographic apparatus, spatial adjustments of its opticalhead to a subject holder obtain along overhead rails which are supportedon a long spanning member embodying interfitted channel members offolded heavy gauge sheet metal, Said spanning member rests at itsopposed ends on two piers each comprising four spaced posts joined bycross beams adjacent their top and base. The composite structure affordsa rigid and stable support for the head such that its film platen andlenses remain coaxially aligned with the subject holder through saidspatial adjustments.

18 Claims, 9 Drawing Figures PATENTEUAFRB I975 3. 724.948

SHEET 1 UF 2 INVENTORS JOSEPH H. WALLY Jr. SAMUEL E. WILSON PATENTEDAPRSms 3.724.948

SHEET 2 OF 2 I4 I4 i 92 9O 2 78 94 n4 5? 78 I6 80 w 80% 5 7O 95 94 a 3l8 62 2 -E 64*) I W FIG. 6 FIG.

l-l //////////////////////Z 66 {82 [82 I00 I04. '06 98 E 5 FIG. '02 I02OVERHEAD RAIL SUPPORTING STRUCTURE FOR PHOTOGRAPHIC APPARATUS Thisinvention relates to photographic apparatus used in making copies oflarge-size graphic sheet material. More particularly, the inventioncomprises novel structure for supporting components including the filmplaten and optics which are adjustably related to the subject holder toaccommodate different magnification and reduction factors in the use ofthe apparatus.

In recent years, considerable demand has been created for apparatuscapable of producing multi-copies of graphic material for bothindustrial and governmental purposes. Many of the original drawings areseveral feet long and correspondingly wide and, depending on a specificneed, the required copies may be to the same scale or on either amagnified or a reduced scale. In addition, with the growing use ofprinted circuitry there has also developed a need for a camera capableof reducing large scale drawn circuits to miniature size on productionline basis but to tolerances sufficiently close that the lines remainabsolutely undistorted and to a precise size. The structure of suchapparatus must be scaled large enough to handle the copy material andthe components needed in photographing such large sized drawings. Theapparatus also must be capable of doing so without introducingdistortion into the projected image. The design and arrangement ofopticsin the apparatus are important in order to avoid possible opticalimage distortion. It is also important that the components not besubject to vibration, sag or other sources of geometric distortion. Inworking with large scaled drawings the latter can be a particularproblem. The present invention, therefore, is particularly concernedwith the elimination of geometrical distortion and the overcomingthereof represents a principal object of the invention.

One photographic apparatus useful for such purposes is disclosed incopending application, Ser. No. 836,317 of Joseph H. Wally, Jr., filedJune 25, 1969,, now U.S. Pat. No. 3,639,054 and owned by our assignee.The photographic apparatus there described embodies an optical headwhich contains a film platen and objective lenses spaced forwardlythereof. The optical head also includes a pair of condenser lenses and aprojector light source disposed behind the film platen so that theapparatus is useful both as a camera and as a projector. With theprojector light source dark the film may'be mounted on the platen andthe apparatus used as a camera by exposing the film through theobjective to reproduce an image of copy material supported on thesubject holder. After the film has been developed it may be relocated onthe platen and the apparatus used as a projector by energizing the lightsource to project an image of the film onto the subject holder. Bylocating light sensitive paper on the subject holder copies of the filmimage may be conveniently reproduced thereby. Within the optical headthe projector light source andobjective lenses are axially adjustablerelative to the film platen to maximize focusing for different spatialsettings of the optical head relative to the subject holder. Becauseboth the film and the developed negative can be located in the sameposition on the film platen and the same optical components are utilizedin both the camera and projector modes the problems of opticaldistortion can be minimized.

In said copending application, the optical head is itself supported fromoverhead rails for movement horizontally as a unit toward and away fromthe subject holder in order to space the film platen for differentdegrees of magnification and reduction, thus permitting copies to bereproduced to the same or different scale as required. The overheadrails along which the optical head moves are described as comprising apair of parallel spaced channel means which are united by end plateswelded to the opposed ends of the channel beams and reinforced byintervening spaced bracing rods so as to form a unitized rigid box-likestructure. One end of the thus constituted rail supporting structure issecured to the subject holder of the apparatus and the end plate of theother end of the structure is bolted to a horizontal cross beam which isfixed between a pair of vertical columns and is braced by piecesinclined between the cross beams and vertical columns.

The present invention improves upon said rail supporting structure andembraces a novel construction therefor which facilitates manufacturingas well as onsite set-up and assembling of the apparatus at the userslocation. It also provides a supporting structure for the optical headwhich is less subject to sway or deflection under the weight ofparticular large sized photographic apparatus and so that geometricdistortion is less a problem when working with the larger sized copymaterial.

The subject holder is mounted vertically as a part of the railsupporting structure and to one side of the working area through whichthe optical head moves in its spatial adjustments. The optical headmoves freely on overhead rails allowing the floor area to remain clearand uncluttered which is particularly important to an operator who mustwork in a dimly lit room in which the apparatus is normally utilized.

For the successful utilization of the apparatus sufficient mass as wellas rigidity must be built into the rail supporting structure in order tocontain the bulk and weight of the optical head over the length of thesupporting stand which is needed to accommodate the travel of theoptical head toward and away from the subject holder in order to permitit a useful range of magnification and reduction factors. In addition,adequate support must be provided for the supporting span so as tominimize the possibility of the span being subject to sway or deflectioneither from external factors or consequent to the load of the opticalhead as it travels along the supporting rails. Thus in one commercialform of the invention wherein the apparatus supports copy material aslarge as 58 X inches and reduces it on film having a nominal image sizeof 10 X 16 inches, the optical head weighs in the order of 1,500 poundsand the span of the overhead rails along which it moves is in the orderof 30 feet.

In such apparatus accuracy in copy reproduction depends on the path ofmovement of the optical head being held constant and in a straight lineat right angles to the subject holder. Only under this circumstance willthe film platen remain vertical and parallel to the subject holder planeand the axial alignment of components of the optical head unchanged withrespect to the subject holder.

Thus a first and principal object of the invention and/or featurethereof is the provision of novel supporting structure which facilitatesrigidly locating and precisely retaining the optical head and therebycoaxial alignment of its film platen and subject holder of suchapparatus in their related adjustments.

A second important object of the present invention is the constructionof rail supporting structure so characterized which also is practicaland efficient to manufacture, as well as convenient to transport and setup at the users location.

In the accomplishment of these objects the invention embodies astructure which comprises a long single spanning member so designed asto resist the weight of the optical head and which rests at its opposedends on separately constructed piers. 1

A feature of the invention is that the piers on which the spanningmember rests comprise four spaced vertical posts united by cross beamsadjacent their top and base. The four posts are widely spaced to providean extremely stable footing, but are not so widely spaced that thestrength of their two cross beams on which the spanning member is restedis taxed by the weight thereof. In accordance with the invention, boththe cross beams and posts are assembled and welded at right angles suchthat they produce an open frame which may be considered as a rectangularparallelepipedonal structure. The two piers have pairs of longer crossbeams which receive, the ends of the spanning member and have shortercross beams which are disposed parallel to the axis of the spanningmember and equidistantly from opposed sides thereof, thus uniformlydistributing the weight of the spanning member and its load between thefour posts while 7 providing resistance to sway and/or deflection of thespanning member under its load.

It is a feature of the invention that the long spanning member itself isconstructed by folding heavy gauge sheet metal stock into inner andouter channel'mem- I bers which are then interfitted and welded togetherin order to form a rigid non-yielding member which spans the separationof the two piers and supports the weight of the optical head withoutfurther reinforcement or underpinning. The inner channel member has alength corresponding to that of the outer member and its upturned sidewalls are welded to the inner surface of the upstanding side walls ofthe outer channel member at a height such that the under wall of theinner member is well spaced above the under wall of the outer channelmember. In addition, the end portions of the side walls of the outerchannel member are folded inwardly along their length and downwardly soas to abut the upper surface of the under wall of the inner channelmember to which they are then welded.

In its preferred form, the under wall of the inner channel member isspaced at a height approximately two-thirds the height of the upturnedside walls of the outer channel member and the downtumed end portionsthereof are inclined at approximately 30 thereto. The rails, in turn,are mounted along the length of the sidewall portions of the outerchannel member immediately above the end wall of the inner channelmember, the boxlike structure formed by the underwalls of the twochannel members and the side walls of the outer member providing ahollow structure which resists sagging. The upturned side walls of theinner channel member and the angled downtumed end portions of the outerchannel member contribute thereto while also affording lateralresistance to retain the rails in a fixed parallel disposition. I

Thus an important feature of the invention is that a rail supportingstructure for the optical head is provided which both facilitatesassembling and also dampens sources of geometricdistortion in theprojected image during use of the apparatus.

A further feature of the invention is that the rail supporting structuredoes not yield to the weight of the optical head and its straight linemovement relative to the subject holder is assured. Therefore the filmplaten and optical components remain in the same aligned relation withthe subject holder through the full extent of the spatial adjustments ofthe optical head relative to the subject holder.

A further feature of the invention is that an overhead rail supportingstructure is provided for the optics of photographic apparatus which isnot subject to deflection and so that distortion in the image producedin the film and/or projected back therefrom to the subject holder isvirtually eliminated.

Still another feature is that in such apparatus in all positions andspatial settings of the film platen relative to the subject holder, thecomponents retain their same coaxial and parallel alignment.

Many other objects, advantages and features of the invention will be atonce apparent or'will become so from a considerationof the detaileddescription of a preferred embodiment of the invention which now will bedescribed. V

Referring therefore now to the drawings wherein like parts areidentified by like reference numerals:

FIG. 1 illustrates photographic apparatus in which the novel overheadrail supporting structure is employed for its optical head;

FIG. 2 illustrates a top plan view thereof;

FIG. 3' illustrates a view of the rail supporting structure partiallyfragmented, the view being considered taken from the left hand side ofFIG. 1 as indicated by the arrows;

FIGS. 4 and 5 are sectional views taken along lines indicated by arrows4-4 and 55 in FIG. 1 and show details in the structure of one of thesupporting piers;

FIG. 6 is a sectional view taken along lines 6-6 indicated in FIG. 1 andillustrate details in construction of the second pier which supports theother end of the long spanning member;

FIG. 7 is a top plan view of the long spanning member, the optical headbeing omitted to permit illustrating details in the guide structureprovided for the electrical and vacuum conduits;

FIG. 8 is a sectional view taken along lines 8-8 of FIG. 1 looking inthe direction indicated by the arrows and shows details in the mountingof the rails to its supporting span member and also shows the opticalhead mounted for travel along said rails; and

FIG. 9 is an enlarged fragmented view illustrating one form of clampemployed in accordance with the invention to stationarily secure theelectrical and air evacuating conduits which lead to the optical head.

Referring now more particularly to the several views, FIG. 1 illustratesphotographic apparatus comprising a camera-projector optical head 12which is supported from parallel spaced overhead rails for movementtoward and away from the subject holder 26 of the apparatus. Theillustrated apparatus other than the rail supporting structure whichcomprises the present invention is disclosed and claimed in theaforementioned copending application, Ser. No. 836,317 to whichreference may be had for an understanding of its construction andoperation. However, for purposes of understanding the present invention,it will sufiice to understand that optical head 12 is suspended by frontand rear wheels 14 which roll along a pair of spaced parallel tracks orrails 16 secured on opposed sides of the overhead rigid supportingstructure 18 which comprises the present invention and is afterwardsmore completely described. Said rigid supporting structure 18 comprisesa long spanning member indicated generally at 20 to which the rails 16are specifically mounted and which spanning member 18 has one end restedon a separately constituted pier 22 and has its opposite end rested on asecond separate constituted pier 24. Pier 24 supports a verticallydisposed subject holder 26 relative to which the optical head 12 movesvia its wheels 14 along rails 16, 16. The optical head 12 contains apair of planoconvex condenser lenses 28, 28 enclosed within a dust tightbox-like enclosure and the optical axis of which is aligned with thecenter of the subject holder 26. The piano side of the first condenser28' is adapted as a film platen 30 to which access is obtained through adoor 32 in plenum 34 of the optical head in order to locate or removethe film or negative from said platen 30. 36 indicates an objective lenswhich is supported by lens board 38 and 40 represents a point source oflight supported by light board 42 behind the condenser lenses 28,28 andthereby the film platen 30. Lens board 38 and light board 42 are mountedon massive size rigid precisely related solid stainless steel precisionrods comprising tubular ways 44 which accommodate axial adjustment ofthe spatial relation of the objective 36 and point source of light 40relative to the film platen 30. It will be understood that each of saidpoint source of light 40, film platen 30 and objective lenses 36 arecoaxially aligned with the condenser lenses 28, 28' and thereby thesubject holder 26 in the proper utilization of the invention.

The subject holder 26, as more particularly illustrated and described inthe aforementioned copending application, preferably comprises aventically disposed translucent member 46 having a vertically planarsurface on its side facing the optical head 12 and surrounding saidmember 46 is a peripherally located continuous channel 48 connected toan air evacuating pump, not shown. At 5 0 is a roll of pliofilm or othersuitable flexible transparent plastic sheet material having one endsecured to the top of the subject holder as illustrated at 50 in FIG. 4.Sheet 50 is positioned and so dimensioned as to overlie the mentionedair evacuating channel 48 about the periphery of the translucent member46 when it is fully unrolled. The sheet material to be copied orsensitive paper in which an image of copies to be printed isinitiallylocated within the area of the translucent member 46 defined by the airevacuating channel 48 and the pliofilm roll 46 is unrolled thereacrossso as to be drawn tightly against the surface of the subject holder 26with evacuation of air from the mentioned channel 48. The unrolledpliofilm sheet thus tightly holds the copy material or sensitive paperagainst the flat vertical surface of the translucent member 36 duringthe photographing or projectionprinting operation.

At 52 are a plurality of fluorescent bulbs supported on pier 24 behindthe subject holder 26 through which its translucent member 46 may beback-lighted. At 54, as illustrated in FIG. 2, are a pair of standssupporting fluorescent light bulbs which may be directed to front lightthe surface of the subject holder 46.

Optical head 12, as thus far described, may be utilized as a camera withits point source of light 40 dark and as a projector with its lightsource 40 illuminated. In its use optical head 12 is moved toward oraway from the subject holder in order to locate its film platen 30 atthe proper spatial setting or distance from the surface of the subjectholder 26 which will introduce a desired image reduction factor when theapparatus is used as a camera or a required magnification factor when itis used as in projection printing. Objective lens 36 is independentlyadjustable toward and away from the film by moving lens board 38 alongways 44. Such adjustment serves to sharpen the focus of the projectedimage at the spatial setting of the optical head 12. Simultaneously withthe axial adjustment of the objective 36 the point source of light 40moves relative to the film platen 30 on said ways 44 so as to provideoptimum light convergence at the nodal point of the objection lensduring projection. 56 represents a motor which is drivingly connected tothe shaft of one pair of wheels 14 to effect movement of the opticalhead 12 along said rail 16. A second motor, not shown, is utilized toeffect spatial adjustment of the objective 36 and point source of light40 relative to the film platen 30 for sharpening focus at each of thespatial settings in which the optical head is located by operation ofthe motor 56.

The present invention is particularly concerned with the illustratedstructure comprising the long spanning member 18 and the two piers 24and 26 on which its opposed ends rest which structure serves to carrythe weight of the optical head as it travels along said rails 16 and animportant feature of the invention, as earlier mentioned, is that thepath of the movement of the optical head does not change from a straightline. Rather, the rail supporting structure is so designed that the pathof the film platen retains a parallel relation to the surface of thetranslucent member 46 of the subject holder and the point source oflight 40, condenser lenses 28, 28 and objective lenses 36, as well asthe film platen, do not vary from their initially determined coaxialaligned relation with the subject holder 26 through the full extent oftravel of the optical head toward and away from the subject holder 26within the limits permitted by stops 58.

Considering now FIG. 3 with FIGS. 1 and 2, it will be seen that inaccordance with this invention rails 16 are bolted at spaced intervalsto the outer side of the upturned sidewalls 62 of the first or outerchannel member indicated generally at 60 so that the upper edges thereofalong which wheels 14 roll protrudes slightly thereabove. In accordancewith this invention, outer channel member 60 comprises heavy gauge sheetmetal stock which has been folded into the cross sectional shapeillustrated by FIG. 3 and comprises a planar or generally flat underwall portion 64 having opposed upturned sidewalls 62 along the lengththereof. The outer ends of said sidewalls 62 are folded inwardly todefine acutely angled portions 66. At 68 is a second channel member alsofolded from heavy gauge sheet metal stock into a generally channel shapein cross section having an under wall 70 and upturned side walls orflanges 72 on its opposed sides. As illustrated, the two channel membersare of comparable length and channel member 70 is located within theouter channel member 60 with its under wall 70 spaced off the under wall64 of the outer channel member, and engaging edge 74 of the inclinedportion 66 along the full length thereof. The upturned side flange walls72 of the inner channel member are welded at its two ends to the innersurface of the upturned side walls 62 of the folded into theirillustrated shapes from heavy gauge sheet metal, the actual gauge ofwhich will vary in ac cordance with the length of spanning member 18 andthe weight of the optical head 12 which it is to support. In onecommercial form of the invention where the "member 18 has a span ofapproximately thirty feet and the optical head weighs in the order of1500 pounds,

the outer channel member 64.comprises. 3/16 inch outer channel member 60and intermittently at points sheet metal and the inner channel member'16 inch sheet metal. In folding the sheet metal into the illustratedchannel shape, it is important that the stock be rolled to avoid sharpcorners and they are deliberately radiused with a radius inside diameterof one-fourth inch or even more. This results in increased strength andresistance to sag. In its preferred form, the upstanding sidewalls 62 ofthe outer channel member have a height roughly equal to one-half thewidth of its under wall 46 and the inner channel member 68 is positionedsuch that its under wall 70 is spaced roughly two-thirds the height ofsaid side wall 62 of the outer member and the upturned side walls 72 ofthe inner channel member 68 extend the remaining one-third height. Thedownwardly turned end portions 66 are preferably so inclined that theyapproximate a 60 angle with respect to wall 70. Although the aboveproportions are to be preferred, they may be varied in accordance withthe invention and in order to meet specific requirements. We have found,however that a spanning member so constructed will have adequatestrength and rigidity to support 'a load in excess of 1,500 pounds asrepresented by the optical head 12 in all positions of spatialadjustments between the piers 22 and 24 without sag or deflection whichwould introduce geometric distortion into the projected image as obtainswhen the optical head is angled at even a small angle ofi parallel.

Piers adequate on which to rest the two end portions of spanning member18 are identified generally at 22 and 24. Each said piers comprise fourvertically extending posts of generally square cross section and haverounded comers. These posts are united by cross beams adjacent their topand base which also are of generally cross section with rounded corners.Two of said posts of each pier are spaced along opposite sides of thespanning member 18 and are joined by shorter beams 82 which are weldedto the respective posts at right angles thereto. The posts of each saidpair further are united by longer cross beams 84 which are similarlywelded to the respective posts at right angles thereto. Each said piers22 and 24 thus generally comprise an open frame structure having theconfiguration of a rectangular parallelepipedon. We have found thisconfiguration for the piers 22 and 24 to provide an extremely stablesupport for the spanning member 18 and its load represented by opticalhead 12 when the respective end portions thereof are rested on the twoparallel spaced top cross beams 84 centered between the posts 80 andarrested in their assembled relation thereon by bolts 86. When thusassembled the shorter cross beams 82 extend generally parallel to thespanning member 18. The two endsof the spanning member 18 are thuseffectively cradled between the four posts and preferably the extensionof the longer cross beams 84 to either side of the spanning memberequals at least the length of the shorter cross beam 82, such that theweight of the spanning member and its load are distributed therebetween.Thus, in the mentioned embodiment wherein the spanning member 18 has aspan of about 30 feet and a width of 16 inches, the longer cross beams84 of pier 22 were 54 inches long and the shorter beams 24 inches. Inthe instance of pier 24, the length of the longer cross beams 84 wasincreased to approximately 150 inches in order to accommodate mountingthe subject holder 26 and also the back lighting members 52 as earlierdescribed. The length of the shorter cross beams 82 was increased to 30inches, both to compensate for the greater length or spacing of theposts to either side of the spanning member and also to accommodatelocation of the back lighting fixtures at a desired distance behind thetranslucent member 46 comprising the subject holder. In said embodimentthe posts 80 and cross beams 82 and 84 of both piers are fabricated of atubular steel having a gauge comparable to that of which the spanningmember 18 is constructed, although it may be of heavier gauge. In theexample, the posts and cross beams had a width on each side ofapproximately four inches. The above described spacing of the postscomprising the two piers was found to produce unitized structures whichwere sufficiently rigid and massive as to provide an extremely stablesupport for the spanning member.

Generally speaking, the greater the spacing of the posts the moreeffective they are in balancing the spanning member against sway andvibration. There are, however, practical limits determined by theinherent capacity of the cross beams 84' to support the spanning memberwithout bending or otherwise yielding to the weight thereof. Theavailable floor space in the area where the apparatus is to be used isalso a factor that needs to be considered.

Considering now FIG. 7 with FIGS. 2 and 3, means are illustrated in theform of a channel member and spaced clamps 92 which function to guideand control the movement of conduits 94 and 96 during the afore-vmentioned movements of the optical head 12. For example, conduit 94represents an electrical conduit through which the light source 40 anddrive motor such as 56 of the optical head are connected to an externalsource of electrical power and 96 represents a conduit which connectsshutter mechanism 37 and platen 30 of the optical head, both of whichare preferably vacuum operated as described in the copendingapplication, Ser. No. 836,317, to the air evacuating pump alsoexternally located. As shown best in FIG. 7, both the electrical contact94 and air evacuating conduit 96 is supported on one of the two inclinedend portions 66 of the spanning member by said clamps 92 for a distanceroughly equal to the distance that the optical head travels along rail16 to its most remote position from the subject holder. Clamps 92 may beof any suitable construction but, as illustrated in FIG. 9, each of saidclamps 92 comprises a continuous resilient loop 98 secured to asupporting base 100 which, in turn, is fastened to one of the inclinedend portions 66 as by screws 102. Mounted on base 100 and protrudingcentrally through loop 98 dividing it into two sections is a threadedstudded member 104 on which is received an internally threaded cap 106.As illustrated by said FIG. 9, conduits 94 and 96 extend through saidloop 100 on opposite sides of stud 104 and so that when cap 106 istightened on stud 104 the two conduits are secured in place and againstmovement. At 108 the conduits are looped back in the opposite directiontoward the subject holder end of the spanning member 18 and secured inplace by a clamp 92 a short distance beyond said loop 108. The twoconduits are again reversely looped as at 110 in the opposite directionaway from the subject holder and lead into channel member 90. Asillustrated by FIG. 7, channel member 90 has spaced flanges 112 by whichit is secured to the inclined end portions 66 of the standing member 18along the opposite side thereof. Channel member 90, as illustrated byFIG. 2, extends the major length of the spanning member 18. However, itsinner wall 114 terminates just beyond clamp 92'. Thus, as indicated bythe full and dash lines, as the optical head moves toward the subjectholder, the end portion of the conduit connected to the optical head arepushed therewith along channel member 90 and is guided by its inner wall114 to a maximum position illustrated by the dash lines. As the opticalhead is moved in the opposite direction away from the subject holder toits most remote position therefrom the connected end portions of conduitare drawn into the channel member 90 to the maximum position illustratedby the solid lines. Thus, conduits 94 and 96 are caused to effectivelyfollow the movement of the optical head and wall 114 acts in cooperationwith clamps 92 to effectively keep the conduit in line and free ofentanglement. Any other arrangement of the electrical and air evacuatingconduits, however,

may be utilized.

From the above description of the preferred embodiments of theinvention, it will be appreciated that all of the recited objects,advantages and features of the invention have been demonstrated asobtainable in a highly convenient and entirely practical manner.

Having described our invention, we claim: 1. In photographic apparatusused to copy graphic sheet material, supporting structure for a pair ofrails along which a support containing a film platen moves relative to asubject holder, said structure comprising a single long spanning memberand a pair of spaced piers on which the two opposite ends of thespanning member rest, the rails being affixed to opposed sides of thespanning member and said spanning member comprising a pair ofinterfitted channel members, the inner channel member having upturnedsidewalls secured to the inside of the upturned sidewalls of the outerchannel member, the underwall of the inner channel member being spacedoff the underwall of the outer channel member, and the end portions ofthe outer channel member being turned inwardly and secured to theunderwall of the inner channel member outwardly of its inturnedsidewalls.

2. Supporting structure according to claim 1 wherein the two piers eachcomprise four vertically spaced posts united by cross beams adjacenttheir top and base, the ends of the single spanning member resting ontwo of the cross beams of each said piers so as to be effectivelycradled between the four vertical posts effectively paired on eitherside of said spanning member.

3. Supporting structure according to claim 1 wherein the two pierscomprise supporting frames having a rectangular parallelepipedonalshape.

4. Supporting structure accordingto claim 3 wherein two sides of saidrectangular parallelepipedonal frames are disposed generally parallel tothe sidewalls of the spanning member and are so spaced as to effectivelyresist swaying of the rail supporting spanning member on said piers.

5. Supporting structure according to claim 1 wherein both the inner andouter channel members of the spanning member comprise heavy gauge sheetmetal folded into said shapes and welded together to constitute a rigidnon-yielding integral structure.

6. Supporting structure according to claim 5 wherein the inturnedsidewalls of the outer channel member meet with the underwall and theinwardly inclined end portions thereof comprise arcuate as opposed tosharply defined comers.

7. In photographic apparatus employing a film platen, an objective and asubject holder in spaced axial alignment, at least one of which ismounted for movement along overhead rails to spatially adjust the platenrelative to the subject holder, the improvement wherein the tails aremounted on a rigid non-yielding structure comprising an elongatedchannel member and a pair of spaced rectangular parallalepipedonalframes on which the respective ends of said channel member rests, theelongated channel member comprising an underwall having upstandingopposed integral sidewalls, the end portions of said sidewalls beingturned inwardly and downwardly at acute angles with respect to saidsidewalls and towards said underwall, and a second reinforcing membersecured within said channel and spaced ofi said underwall, said secondmember being also secured to said inwardly and downwardly turned endportion of the channel member sidewalls.

8. The improvement of claim 7 wherein the second member disposed withinthe channel member is of channel shape and has a bottom wall in spacedrelation off the underwall of the channel member and has opposed sideswelded to the edges of the inwardly turned end portions of the channelmember, said second member having its edges disposed against and weldedto the inner surfaces of the opposed sidewalls of the channel member.

9. The improvement according to claim 7 wherein said second member hasopposed side flanges which are disposed against and welded to the innersurfaces of the opposed sidewalls of the channel member.

10. The improvement according to claim 7 wherein one of said rectangularparallelepipedonal frames supports the subject holder.

11. The improvement according to claim 8 wherein the subject holder istranslucent and the said rectangular parallelepipedonal frame whichsupports it also has means spaced behind the subject holder for rearlighting the subject holder.

12. The improvement according to claim 7 wherein the platen andobjective are supported within an optical head which moves along saidrails.

13. The improvement according to claim 7 further including channel guidemeans extending lengthwise thereof for guiding electrical conduits whichconnect to the optical head and are pushed and pulled with the movementof the optical head toward and away from the subject holder.

14. The improvement according to claim 1 wherein the upturned sidewallsof the inner channel member extend upwardly to adjacent the junction ofthe inclined end portions of the outer channel member with its sideportions.

15. The improvement according to claim 14 wherein the rails are boltedto the upturned sidewalls of both the inner and outer channels atlocations above the underwall of the inner channel member.

16. The improvement according to claim 1 wherein theunderwall of theinner channel member is spaced off the underwall of the outer channelmember. a distance equal to approximately twice the remaining height ofthe sidewalls of said outer channel members.

17. Supporting structure according to claim 1 wherein the upturnedsidewalls of the outer channel member approximate one-half the lateraldimension of

1. In photographic apparatus used to copy graphic sheet mateRial,supporting structure for a pair of rails along which a supportcontaining a film platen moves relative to a subject holder, saidstructure comprising a single long spanning member and a pair of spacedpiers on which the two opposite ends of the spanning member rest, therails being affixed to opposed sides of the spanning member and saidspanning member comprising a pair of interfitted channel members, theinner channel member having upturned sidewalls secured to the inside ofthe upturned sidewalls of the outer channel member, the underwall of theinner channel member being spaced off the underwall of the outer channelmember, and the end portions of the outer channel member being turnedinwardly and secured to the underwall of the inner channel memberoutwardly of its inturned sidewalls.
 2. Supporting structure accordingto claim 1 wherein the two piers each comprise four vertically spacedposts united by cross beams adjacent their top and base, the ends of thesingle spanning member resting on two of the cross beams of each saidpiers so as to be effectively cradled between the four vertical postseffectively paired on either side of said spanning member.
 3. Supportingstructure according to claim 1 wherein the two piers comprise supportingframes having a rectangular parallelepipedonal shape.
 4. Supportingstructure according to claim 3 wherein two sides of said rectangularparallelepipedonal frames are disposed generally parallel to thesidewalls of the spanning member and are so spaced as to effectivelyresist swaying of the rail supporting spanning member on said piers. 5.Supporting structure according to claim 1 wherein both the inner andouter channel members of the spanning member comprise heavy gauge sheetmetal folded into said shapes and welded together to constitute a rigidnon-yielding integral structure.
 6. Supporting structure according toclaim 5 wherein the inturned sidewalls of the outer channel member meetwith the underwall and the inwardly inclined end portions thereofcomprise arcuate as opposed to sharply defined corners.
 7. Inphotographic apparatus employing a film platen, an objective and asubject holder in spaced axial alignment, at least one of which ismounted for movement along overhead rails to spatially adjust the platenrelative to the subject holder, the improvement wherein the rails aremounted on a rigid non-yielding structure comprising an elongatedchannel member and a pair of spaced rectangular parallalepipedonalframes on which the respective ends of said channel member rests, theelongated channel member comprising an underwall having upstandingopposed integral sidewalls, the end portions of said sidewalls beingturned inwardly and downwardly at acute angles with respect to saidsidewalls and towards said underwall, and a second reinforcing membersecured within said channel and spaced off said underwall, said secondmember being also secured to said inwardly and downwardly turned endportion of the channel member sidewalls.
 8. The improvement of claim 7wherein the second member disposed within the channel member is ofchannel shape and has a bottom wall in spaced relation off the underwallof the channel member and has opposed sides welded to the edges of theinwardly turned end portions of the channel member, said second memberhaving its edges disposed against and welded to the inner surfaces ofthe opposed sidewalls of the channel member.
 9. The improvementaccording to claim 7 wherein said second member has opposed side flangeswhich are disposed against and welded to the inner surfaces of theopposed sidewalls of the channel member.
 10. The improvement accordingto claim 7 wherein one of said rectangular parallelepipedonal framessupports the subject holder.
 11. The improvement according to claim 8wherein the subject holder is translucent and the said rectangularparallelepipedonal frame which supports it also has means spaced behindthe subject holder for rear lighting the subject holdEr.
 12. Theimprovement according to claim 7 wherein the platen and objective aresupported within an optical head which moves along said rails.
 13. Theimprovement according to claim 7 further including channel guide meansextending lengthwise thereof for guiding electrical conduits whichconnect to the optical head and are pushed and pulled with the movementof the optical head toward and away from the subject holder.
 14. Theimprovement according to claim 1 wherein the upturned sidewalls of theinner channel member extend upwardly to adjacent the junction of theinclined end portions of the outer channel member with its sideportions.
 15. The improvement according to claim 14 wherein the railsare bolted to the upturned sidewalls of both the inner and outerchannels at locations above the underwall of the inner channel member.16. The improvement according to claim 1 wherein the underwall of theinner channel member is spaced off the underwall of the outer channelmember a distance equal to approximately twice the remaining height ofthe sidewalls of said outer channel members.
 17. Supporting structureaccording to claim 1 wherein the upturned sidewalls of the outer channelmember approximate one-half the lateral dimension of the underwallthereof.
 18. Supporting structure according to claim 1 wherein theinclined end portions are disposed at approximately thirty degrees withrespect to the upturned sidewalls of said outer channel member.